x86/entry/64: Push extra regs right away

(cherry picked from commit d1f7732009e0549eedf8ea1db948dc37be77fd46)

With the fast path removed there is no point in splitting the push of the
normal and the extra register set. Just push the extra regs right away.

[ tglx: Split out from 'x86/entry/64: Remove the SYSCALL64 fast path' ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Link: https://lkml.kernel.org/r/462dff8d4d64dfbfc851fbf3130641809d980ecd.1517164461.git.luto@kernel.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 2c154c980543b35e869edbd1bf2debc812456ee7..db5009ce065aac6cc8b214f4d072d6e0723f4211 100644 (file)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -177,10 +177,14 @@ GLOBAL(entry_SYSCALL_64_after_swapgs)
        pushq   %r9                             /* pt_regs->r9 */
        pushq   %r10                            /* pt_regs->r10 */
        pushq   %r11                            /* pt_regs->r11 */
-       sub     $(6*8), %rsp                    /* pt_regs->bp, bx, r12-15 not saved */
+       pushq   %rbx                            /* pt_regs->rbx */
+       pushq   %rbp                            /* pt_regs->rbp */
+       pushq   %r12                            /* pt_regs->r12 */
+       pushq   %r13                            /* pt_regs->r13 */
+       pushq   %r14                            /* pt_regs->r14 */
+       pushq   %r15                            /* pt_regs->r15 */
 
        /* IRQs are off. */
-       SAVE_EXTRA_REGS
        movq    %rsp, %rdi
        call    do_syscall_64           /* returns with IRQs disabled */